1. Field of the Invention
This invention relates to certain antigens and antigen conjugates, and to their method of manufacture, useful, in particular, in the production of high titers of antibodies, to the production of these antibodies, and to the use of these conjugated antigens in the immunotherapeutic treatment of cancer.
2. Description of the Prior Art
Immunity is an everyday word applied to a special category of defenses possessed by the body by means of which infectious agents may be checked or destroyed even after they have entered the body tissues. When a person or animal becomes immune to a disease, the immunity is largely due to the development within the body of substances capable of destroying or inactivating the causative agent of the disease, should it gain access to the body at a later time. These substances, known as antibodies or immune bodies, are produced by the body in response to a specific stimulus. Microbes and their products within the body may stimulate the body cells to antibody production. Other substances that may accomplish the same effect include red blood cells and serum from other animals, and other proteins. These substances are collectively known as antigens and are generally of high molecular weight substances of a protein nature, but in some cases complex carbohydrates (polysaccharides) may act as antigens.
Antigens are substances that stimulate the formation of antibodies within an animal and react observably with that antibody. They generally possess a high molecular weight of 10,000 or more. While the list below is not meant to be all inclusive (a detailed description is set forth in P. L. Carpenter, Immunology and Serology, 2nd Edition, 1968), typical antigens may be classified as follows:
(1) protein antigens, such as ceruloplasmin and serum albumin; PA1 (2) bacterial antigens, such as teickoic acids, flagellar antigens, capsular polysaccharides, and extra-cellular bacterial products and toxins; PA1 (3) blood group antigens, such as glycoproteins and glycolipids; PA1 (4) viruses, such as animal, plant, and bacterial viruses; PA1 (5) conjugated and synthetic antigens, such as protein-hapten conjugates, and synthetic polypeptides; and PA1 (6) nucleic acids, such as ribonucleic acid and deoxyribonucleic acid.
Immunity may be natural or acquired, and in the latter case may be acquired naturally or artificially. Artificial immunity, as is well known, can be either passive, i.e., by injection of an antiserum (prophylactic, therapeutic), or active, as by vaccination with, for example, live or dead organisms.
Immunization procedures are important in the prevention of various diseases including viral diseases. There is also considerable evidence that viruses do cause various kinds of tumors and cancerous growths, particularly in lower animals such as rabbits, mice, chickens, and hamsters. Various investigators, including the present applicant, have also been active in their attempt to discover agents that might be effective in cancer immunotherapy. See Lekhite, V. V., "Clinical Cancer Immunotherapy: Experience in Breast and Lung Cancer," in Immunocancerology in Solid Tumors, (Martin, M. and Dionne, L., eds.) pp. 135-141. (Stratton, 1976). "Rejection of Tumor Metastases in Fisher 344 Rats Following Administration of Killed Corynebacterium parvum," Cancer Immunology and Immunotherapy, (1977), Vol. 2, pp. 173-178. V. V. Likhite.
In response to an injection of antigens, the body of an animal produces specific antibodies which react with and neutralize the antigens. Antibodies are classified as proteins with the solubility of globulins and the electrophoretic mobility of gamma globulin. The molecular weight of gamma globulins, or as they are also called "immune globulins," varies from 160,000 to 1,000,000 and these immune globulins (Ig) are subgrouped into five classes, according to molecular weight, i.e., Ig G, Ig A, Ig D, Ig E, and Ig M. The Ig G class, or group, is the most prevalent in serum and is characterized by a molecular weight of 160,000. The Ig M class is the least prevalent and is characterized by a molecular weight of 1,000,000.
Sometimes it is necessary that a large supply of antibodies appear in a person's blood immediately in order to combat an overwhelming infection already present in the body. Accordingly, the patient must receive ready-made antibodies, and various means are known for the manufacture and recovery of antigens and antibodies, these being merely exemplified by U.S. Pat. Nos. 3,652,761 and 3,843,444.
In U.S. Pat. No. 3,652,761, there is disclosed an immunochemical composite comprising an antigen or antibody chemically coupled to an inorganic carrier. As the antigen or antibody becomes insolubilized, when so coupled, this, according to the patentee, provides a better means of recovery of a more pure antigen or antibody.
U.S. Pat. No. 3,843,444, which issued to applicant on Oct. 22, 1974, discloses a means for concentration, separation, and recovery of macromolecular substances having mutual attraction for one another, particularly biological substances such as antibodies and antigens. The invention makes use of the discovery that antigens and antibodies, which are specific for one another, can be preferentially attracted to opposite surfaces of thin semipermeable members.
These various known procedures for manufacture and recovery of antigens and antibodies, while satisfactory to a degree, are attendant with certain disadvantages. One major disadvantage with some prior known systems results from the fact that antigens and antibodies are mutually attracted to one another. This attraction interferes with purification and recovery of antibodies. The recovered product, in many instances, has been markedly reduced to a fraction, e.g. 5-20%, of the original physiological activity. When an animal receives repeated injections of a given antigen, the induced specific antibody response in the host animal against the injected antigen represents a relatively small amount, usually less than 1%, of the serum globulin pool. The quantitive response, moreover, has not been improved beyond the host capabilities.
There is a need, not only for a method of producing larger quantities of antibodies within a biological system, but also improved methods of recovery of antibodies without loss of appreciable activity.